In various well operations such as the pressure testing of pipe that is being lowered into a well, it is necessary to position a pack-off tool in the interior thereof so that fluid under pressure can be used to detect leaks or other defects. In order to remove the tool from the pipe, or to move it to another location therein, it generally is necessary to engage an overshot with a fishing neck on the upper end of the tool and apply upward force to cause release thereof. The various types of overshots which have been used in the past have a number of shortcomings. Many devices employ one or more shear pins or other frangible restraining means that require a jarring action to be applied in the operation of the tool. This type of tool is quite complex in structure and operation and is relatively expensive to manufacture and to maintain. Other devices have gripping members with a scissor-like configuration, and are subject to being broken off in use which renders them inoperable to catch or to hold the fishing neck of the tool that is to be moved in the pipe.
It is the general object of the present invention to provide and a new and improved retrieving apparatus of the type described.
Another object of the present invention is to provide a new and improved overshot apparatus that is relatively simple in construction and operation, and which does not employ shear pins or like elements in the operation thereof.
Another object of the present invention is to provide a new and improved retrieving tool that still will remain connected to the fishing neck of an associated well device even though a gripping member has been inadvertently broken in use.
Still another object of the present invention is to a new and improved retrieving tool of the type described that is more simple in construction and reliable in operation than prior devices.